Liquid level contactor



D 1950 s. KONGELBECK 2,

LIQUID LEVEL con'rAcToR Filed'Oct. 7, l947\ lllllll IN VEN TOR.

fiverrefzoqgyd, BY

Patented Dec. 26 1950 LIQUID LEVEL CONTACTQB Sven e iiongelbcck,Chicago, Ill., assignor to Infilco Incorporated, Ch

of Delaware icago, 111., a corporation Application October 7, 1947,Serial No. 778,344

1 12 Claims This invention relates to a contact member for a liquidlevel gauge of the type described in the copending application of S. ,L.Adelson, Serial No. 705,577, now Patent No. 2,496,366, granted Feb. 7,1950.

The Adelson application, above mentioned, relates t an appa atus forineasu ine'the level f a liquid utilizing a single contact whichdirectly or indirectly contacts the liquid .suriace, and

,- which is automatically raised or lowered so as to follow the.1iquidsurfa ehe a pa atus in its preferred form comprises a pair ofunidirectional moto s in opposed relationsh p, p ratively onnected to adifferential gear arrang ment whereby a gear case will rot in one d r cton or t e.

ther depending upon which motor is runn ng a a greater speed than theother, but which will re,

ma n m t onless when both motors rotate at the same spe dhis appara usut liz a ashtron, which is an electronic device providing twoimmediately responding, inertialess relays. An element of the Flashtronis an actuator circuit which when closed externally (even through arestance as large as 20,000 ohmsf) will render only one of the relaysconductive while if the actuator r uit is oken, only the other of the rays will be rendered conductive. Thus one or the other of the relays isalways conductive depending upon whether the actuator circuit is open orclosed. The relays control delivery .of power to the electric motors, sothat one or the other of the motors will have power applied to it, Theactuator circuit in the Adelson device includes the liquid whose levelis to be measured and a contact mem, ber carried on a contact rod whichis raised and lowe ed by ove nt f t e sear caee- Thus when the c act enges the liquid su face one of the motors will be actuated to li t the rodand contact, and will so operate until th contact is broken. Thereuponthe actuato cir u t i roken and the other of the motors begins tooperate a reverse direction to lower the contact until it a ai enga esthe liqu d suriace- Thus the e is a onti ual and very sl ght mo ement othe contact rod to make and break a circuit includns the contact and theliquid surface, In vAdel- ,sons preferred form he utilizes a floatcarried by the liquid surface so that contact is not made directlybetween the contact rod and e liquid surface, as he found that the floataccurately measu ed variati ns in the iq id surface of /1009 of an inchwhi e a direct whisker c ntact with the liqu d ur ace as accura e onlyto not of an inch- In some installations the space requ rement or thefloat operated contact renders th form undes rable because the float mut be o o e si i order to arry he nec ssary con a st u t re and thereforerequires a basin of some size in which to operate, Obviously the largerthe basin t e more liquid is required in order o r se he l qu d sur cewh ch in some n a on m an h t t e hde son mete wil be s o i respon i gto the chan es in the qu d le el to e e sured- On the other hand awhisker dipping directly nto the liquid su iaee is objec ionabl c s hhat type of contact the e is a n t n d considerable fluctuation of thecontact rod which in o es on idera le weer on the part o he meter andalso renders it somewhat inaccurate.

he primary obje t of my inven ion is to p -c vide a contact for acontact gauge, of which the Adelson meter is one example, whicheliminates reciprocation of the con act positioning mechanism andthereby provides a more accurate reading while involving less movementof the motors and the connecting mechanism. It will be obvious from thedescription that follows that'the contactor of my invention can be usedin any gauge, or meter, operative toindlcate the position, or change ofposition, of any surface. Such a gauge can be used to indicate theposition of a movable solid surface, the gauge operating by movement ofa contactor which alternately engages and disengages the surface to bemeasured.

Another important object of myvinvention isto provide a contact memberfor use in a liquid level gauge, such as the ,Adelson type, which is asaccurate as the float contact preferred by Adelson, but which does notinvolve a float and its consequent relatively large basin, and whichpractically eliminates the constant reciprocation of a whisker typecontact.

Th se and other ob ec s i b ap a e t om the e cr ption and c aims h chfollow- The e ror in the whis er ty of ntac and the re at y l e magniude of reci rocation involved with tha ty of con act, is probably due tothe Iorrnsti h o a meniscu round the whisk r when the wh ker nter the lquid s r fa e and as i lea es it, It i well known h t a very n ticeableconcave meniscu s formed a a h ker enters the liq id ur ac due t t e sura e ion f t e li uid opp sing re enetraion of the l q i by the h skerand that a con: vex men scus is i mod round th hisker nd esp cia ly asit is w thdraw om the l quid due to t attract on of th liquid for thewhisker- The vertical distahoe between the two extremes is considera leand involv s onsequent error in operation of the Adelson meter with awhisker type contact, and also involves constant reciprocation ofconsiderable magnitude of the contact rod.

My invention will be readily understood from consideration of thefollowing detailed description and of the drawings which form a partthereof and in which:

Figure 1 is a view of a preferred form of contact member;

Figure 2 is a side view of the contact member of Figure l and theassociated driving member;

Figure 3 shows another embodiment of a contact member of my invention;

Figure 4 shows another form of contact member;

Figure 5 is a side view of the form shown in Figure 4;

Figure 6 illustrates the concave meniscus customarily formed as awhisker type contact is engaging the liquid surface;

Figure 7 shows the convex meniscus formed around the whisker as thewhisker is being withdrawn from the liquid.

The advantages of my invention will be more readily understood if wefirst consider the disadvantages of the whisker type contact member, andthe accompanying meniscus, which are illus trated in Figures 6 and 7. Asabove indicated a contact rod [6 is raised and lowered with respect toliquid surface by means of a gear cage between two opposedunidirectional motors which are alternately actuated as an actuatorcircuit through the contact rod l6 and the liquid is made or broken.Such details of the meter devic itself are not a part of my inventionand are described in the copending application of Adelson, abovementioned. Let us assume that the lower end of the contact rod isprovided with a fine wire, or whisker, IT to make the contact with theliquid surface l8. As the rod I6 is lowered the tension of the surfac ofthe liquid film l8 opposes penetration by the whisker ll, therebyforming a concave meniscus [4 of a depth h In many instances the tip ofthe whisker I! may become corroded so as to interfere with a proper.closing of the actuator circuit when the end of the whisker firsttouches the liquid surface and before the whisker itself actually iswetted. Upon the closing of the actuator circuit through the contact rod[6, the whisker l1 and the liquid 18, the flow of power to the firstmotor is stopped and that to the second motor begun, thereby raising thecontact rod l6. However, as the whisker H is withdrawn from the liquidit forms a convex meniscus l5 of a height h as shown. Obviously theactuator circuit will not be broken until the convex meniscus i5 isbroken, which corresponds to travel of the probing rod IE equal to hThus the actuator circuit may be closed improperly for as long as ittakes the whisker I! to rise the vertical distance h +h In such acondition it will requir a corresponding length of time of downwardtravel of the probing rod [6 before the whisker will again close theactuating circuit. In such cases the error is due to the necessity ofthe contact traveling th distance h -l-h in order to break and make thecontact. However, even if the actuating circuit is closed as soon as thewhisker touches the liquid surface, there still remains the inaccuracydue to the convex meniscus (equivalent to In). In meters of this type itis desired that the motion of the contact rod, or probe, It be ratherslow, in fact to be at the lowest figure possible,

having consideration for the maximum rate of level change and thenecessity of having an immediate response thereto. It is thereforeobvious that there will be a constant and considerable fluctuation, orhunting, of the probe l6 when the usual type contact is used.

I have found that if instead of the simple whisker type contactheretofore used, which is moved vertically to and from the liquidsurface by the actuator of the level sensing mechanism, an independentlypower driven movable contact member is provided which travels fastenough to avoid formation of a meniscus and which makes and breakscontacts at high frequency, the meter not only is more accurate but thatfor all practical purposes the probing rod 16 is stationary so long asthe liquid level remains unchanged. Such movable contact members sliceor cut the surface film at a velocity which avoids the formation of ameniscus, either concave or convex, and also provide a system wherebythe time between contacts is radically reduced, and the level sensingmechanism will receive contradictory signals at a high frequency so asto avoid overtravel and the consequent errors resulting therefrom. Thiswill be obvious from a consideration of the forms of contacts shown inthe drawings.

A preferred form is shown in Figures 1 and 2 and comprises a small motor23 and gear reducer, not shown, mounted in a preferably water-tight cage29 at the lower end of the contact rod 16. Upon the shaft 2! driven bythe motor and gear reducer is mounted a small wheel 22. Upon the wheel22 are mounted a number of arms 23 carrying contact whiskers 24 at theirouter ends. The arms 23 are preferably made adjustable with respect tothe wheel 22 as by threading the inner ends 25 of the arms 23 intosimilarly threaded portions 26 of the wheel, and locking them in theirproper positions by lock nuts 21.

The small drive motor for rotating the contact member is constantlconnected to a source of power so that it operates continuously. I havefound that a very suitable rate of rotation of the contact member havingeight arms, as shown in Figures 1 and 2, is about revolutions per minutewhen the arms are 1 inches long. At this rate there obviously will be800 contacts per minute or a little more than 13 per second. Suchcontacts not only follow each other in rapid order but each contact isquickly made and immediately broken by the travel of the whisker. Themaking and breaking of the actuator circuit at this rapid rate keeps thetwo motors a quiver" or alert, but does not give either a chance toactually respond (except when the liquid level itself is changing).Thus, with the contact member of my invention the contact rod i6 isstationary so long as the liquid level is station. This provides formore accurate measurement with less wear and lower power requirement ofthe response mechanism than heretofore. The number and radial length ofthe arms, and their angular velocity can be varied as desired. Howeverany variation in on factor should be compensated for by a modificationof one or both of the others in order to keep fairly constant therelation between length of contact and length of no contact.

A second form of contact member is shown in Figure 3 and comprisessimply a solid wheel 30 mounted on the shaft 2|. The peripheral edge ofthe wheel is provided with a plurality of knife edged projections 3|,which may be as small as can:

1% or A; of an inchin' height. iAs the. wheel revolves the knife edgeslot-the projections" ll. cut the liquid surface, thereby closing the.ao'tu ator circuit. This form isof value when'it is desired to form acontact for :a short period of time. Also, in case of a sudden surgeupward of theliquid level the solid part of the disc will form acontinuous contact with the liquid and thus give a continuous retractsignal toithe response mechanism untiTequili-brium is again established.It is obvious that the whisker type shown in Figure lwill form amomentary contact with the liquid only, whilethe projections 3| ofFigure .3, relatively speaking, a prolonged contact with a short breakbetween. succfisslvecntacts. I

Figures 4 and '5 show a front and'side view, respectively, of anotherform of contact- 'meni-' her, which has certain advantages. Inthisembodiment the contact member 45 comprises a knife edged wheel of a.radius R... The wheel is mounted upon a shaft 21, the mounting beingeccentric to the center of the wheel by, some predetermined distance aIf the eccentric wheel is not rotating, then it will contact anddisengage the liquid surface the same as the whisker of Figures 6 and 7.In such an event, theffrequency of contact would be the same as that ofa simple contact member, or whisker. However, upon rotation of the wheel40 the eccentricity thereof causes a variation in level of the wheelperiphery (assuming the elevation of the shaft 2| remains constant)equal to 2e. Functionally, the wheel 40 operates as a wheel with aradius R-e, with a single projection of a height of 2c. Thereforerotation of the eccentric wheel gives an effect similar to that of theother two embodiments shown, In effect acting as a wheel with one .armor contact. It will be obvious that the frequency of contact will bedirectly proportional to the speed of rotation of the wheel. This formhas the advantage of being the cheapest to construct, and it worksbetter with only a slight reduction of motor speed (saving expense inthe speed reducer required). The results, frequency and accuracy ofcontact, are very satisfactory.

It will be obvious that the relative size and shape of the contacts 24or 3|, or the amount of eccentricity e of the wheel 40, can be modifiedas desired according to the requirements of any particular case. Theycan provide momentary contact as with a whisker, such as 24, or they canprovide somewhat prolonged contact, as with a relatively long projection3|. The number of contacts will depend on the rate of rotation, and thelength of the period between contacts will depend on the spacing betweencontacts. Thus, the length of contact, number of contacts and timebetween contacts can be proportioned as desired. Such proportioning ofthe actual contact member, and the number to be mounted upon the wheel,will be obvious to those skilled in the art, having due regard for therequirements for each installation. Obviously many modifications andvariations in the invention herein set forth may be made by personsskilled in the art without departing from the spirit and scope hereof.Also it will be obvious that this invention is applicable to a gauge formeasuring the relative position or movement of any surface, andtherefore its application is not limited to the Adelson liquid levelgauge mentioned. It is therefore to be understood that my invention isnot limited to use with any particular apparatus or used for anyparticular purpose, but is to 6: be construed. as broadly as defined inthe claims.

I claimel. A contact member for a liquid level meter 7 of the typedescribed comprising. a rotatable shaft mounted for vertical movementwith respect to the liquid surface to be measured, a revolvable membercarried at the end of saidshaft, a contact mounted on said revolvablemember, means for continuously revolving said shaft and said member,said contact alternately engaging and disengaging the liquid surfaceupon rotation of said revolvable member, and means operative to raiseand lower said shaft in response tovariations of said liquid surface tomaintain a constantdistance between said liquid surface and said shaft.2. In a liquid level meter of thetype described a contact membercomprising a wheel mounted for rotation around a horizontal axis, aplurality of arms mounted on said wheel, and a whisker contact mountedat the outer end of each of said arms, means to rotate said wheelcontinuously around said axis, and means for raising a'nd lowering theaxis of said wheel in response to variations in the liquid level to bemeasured, to keep the distance between said axis and said liquid levelsubstantially constant.

3. Apparatus according to claim 1 wherein said revolvable membercomprises a wheel, and a plurality of knife edges mounted on theperipheral edge of said wheel.

4. Apparatus according to claim 1 wherein said revolvable member is awheel having at least one knife edge mounted on its peripheral edge andsaid knife edge has a portion with a radial distance from the center ofrotation of said wheel greater than that of other portions of theperipheral edge of said wheel.

5. Apparatus according to claim 2 wherein the number of arms on saidwheel and the speed of rotation imparted to said wheel are proportionedto result in about thirteen contacts per second.

6. The apparatus of claim 2 wherein the means for rotating said contactmember operates to move the contact member through a vertical rangegreater than that of the required accuracy of position measurement.

'7. In an apparatus for measuring the position of a surface by moving acontact means toward and away from the surface the position of which isto be measured, the contacting of said surface with said contact meanscausing the contact means to move away from said surface and thebreaking of said contact between said surface and said contact meanscausing the contact means to move toward said surface, a contact meanscomprising a horizontal rotatable shaft, a plurality of spaced contactpoints affixed to said shaft and rotatable in a vertical plane uponrotation of said shaft, supporting means for said shaft operative inresponse to variations in the position of the surface to be measured toraise and lower said shaft to keep the distance between said surface andsaid shaft substantially constant, and means for continuously rotatingsaid shaft independently of any movement of said supporting means at avelocity sufficient to make and break contact with said surface at highfrequency.

8. In an apparatus for measuring the level of a movable surface, a,rotatable member, means for rotating said member around a horizontalaxis, means responsive to variations in the surface level to be measuredand operate to raise and lower said rotatable member in response to suchvariations to maintain the distance of its axis of rotation from thelevel of said movable surface substantially constant, and a contactcarried at the periphery of said member.

9. Apparatus according to claim 8 wherein said rotatable membercomprises a contact wheel eccentrically mounted on said horizontal axis.

10. Apparatus according to claim 8 wherein said rotatable member carriesat its periphery a plurality of contacts.

11. In an apparatus for measuring the level of a liquid surface whichincludes a probing rod adapted to be moved to and from the surface thelevel of which is to be measured, the contacting of said surface withsaid probing rod causing the rod to be withdrawn from said surface andthereby to break the contact between the two and the breaking of thecontact between said surface and said rod causing said rod to be movedtoward said surface, a contact member connected to said rod, said memberbeing mounted on said rod for rotation in a vertical plane, saidrotation being independent of, and in addition to, any motion impartedto said contact member by said rod, and means for continuously rotatingsaid contact member at a velocity sufiicient to make and break contactat high frequency.

12. A surface position gauge including a shaft,

aimotor in driving connection with said shaft and operative to impartcontinuous motion to said shaft, a contact member mounted at the end ofsaid shaft, said member making and breaking contact withsaid surfaceupon movement of said shaft by said motor, and means operative upon achange in the elevation of said surface to move said contact membervertically into position to make and break contact with said surface atthe new elevation.

. SVERRE KONGELBECK.

REFERENCES CITED '{Ihe following references are of record in the file ofthis patent: I

UNITED STATES PATENTS Number Name Date 468,120 Thomson Feb. 2, 1892663,695 Davidson Dec. 11, 1900 724,704 Hutton Apr. '7, 1903 2,032,016Hitner Feb. 25, 1936 2,059,152 Smith Oct. 27, 1936 FOREIGN PATENTSNumber Country Date 20,670 Great Britain 1907

